Ten-year-old George Calder is the luckiest boy alive. He and his eight-year-old sister, Phoebe, have just spent two months with their aunt in England. And now they all get to travel back to New York on a boat. And not just any boat—the Titanic!

In 1912, the Titanic was the largest and most beautiful ship in the world. It had a swimming pool, three dining rooms, and could hold over 2,000 people. And what luck that George and his family were going to be on the Titanic for its very first voyage!

After the Titanic departs for the United States, George starts exploring the ship and quickly finds ways to get into trouble. When he learns that there might be a mummy on board, he can't help himself. He has to find the mummy and see it for himself. But while down in the storage area, George is rattled by loud noises and then, silence. After running upstairs, he discovers that the Titanic hit an iceberg.

At first it's funny. Everyone is joking and laughing and throwing ice balls at each other! But soon it becomes apparent that the ship is sinking. And with only 16 lifeboats, there is no way that everybody on the ship will be saved.

After George's sister goes missing, he and his aunt run around the ship trying to find her. Will they be able to reach Phoebe in time, or will she sink along with the Titanic?